This invention relates generally to spring assemblies for use in mattresses, spring upholstered furniture and the like and, more particularly, to a posturized pocketed coil spring assembly and associated method of manufacturing such an assembly.
A well known type of bedding or seating product comprises a spring assembly which includes a number of discrete coil springs, each of which is enclosed in a fabric pocket in a length of folded fabric material. Longitudinal axes of the coil springs are generally parallel with one another so that the top and bottom end turns of the coil springs define top and bottom faces of the spring assembly. A row of such pocketed springs is known in the industry as a string of pocketed springs. A bedding or seating product can be fabricated from such strings of pocketed springs by binding or adhering the individual rows or strings of pocketed springs together to form a spring assembly which may be padded and encased in an upholstered covering. U.S. Pat. No. 6,143,122 discloses one such method of adhesively bonding strings of pocketed springs together to form a spring assembly.
This type of spring assembly is commonly referred to as a pocketed spring unit due to the fact that each spring is contained within an individual pocket of fabric material. The construction of strings of pocketed coil springs in each pocket is well known in the art and, for example, is disclosed in U.S. Pat. No. 4,439,977 which is hereby incorporated by reference in its entirety. The system disclosed in that patent includes a spring coiler which forms a coil spring which is subsequently compressed and inserted between the plies of folded pocketing fabric material. Other systems for manufacturing pocketed coil spring assemblies are disclosed in PCT Patent Application No. WO94/18116 and U.S. Pat. No. 6,101,697, each of which are expressly incorporated herein by reference.
Pocketed spring assemblies are generally recognized to have a unique and particular luxurious feel to them and mattresses manufactured of such pocketed spring assemblies provide a feeling of softness without lacking spring resilience or support. Mattresses and similar articles constructed of pocketed spring assemblies are often considered a high-end type of product because of the added benefits and features of the pocketed coil springs. Mattresses and the like of this type can be more costly to manufacture and assemble as a result of the considerable amount of time and labor which is involved in their manufacture, together with the fact that the method of fabrication and assembly of such pocketed spring assemblies can be complicated, particularly in an automated process.
One particular aspect of the commercial production of pocketed spring assemblies and the associated mattresses or the like is the handling of such assemblies in the factories. The manipulation and movement of the various components of the spring assembly from station to station or various areas of the factories can be cumbersome, difficult and inconvenient depending on the particular production facilities and assembly techniques.
Additionally, while pocketed spring assemblies are considered to provide a combination of softness and support, the ability to economically posturize a spring assembly or mattress of pocketed spring coils has heretofore been difficult. Posturization provides multiple zones or sections of differing firmnesses within a product such as a mattress. For example, the middle regions of the mattress, which typically support a person""s torso, often require a firmer more resilient support while other areas of the mattress which support the feet and head of a person require a softer feel.
One known method of posturizing a pocketed spring unit has been to incorporate springs made of different gauge wire into the strings of springs. For example, the springs incorporated into the strings of springs within certain sections or zones of the spring assembly are made of a larger gauge wire than the springs incorporated into the strings of springs of the other sections or zones of the spring assembly. U.S. Pat. No. 6,173,464 discloses this concept, albeit with continuous bands of springs as opposed to individual springs.
Therefore, there is a need for a posturized pocketed spring assembly and associated method of manufacture which offers the advantages of posturization of the spring assembly without the higher manufacturing costs, production difficulties and inefficiencies associated with known posturized pocketed spring assemblies.
The invention of this application which accomplishes these and other objectives comprises a bedding or seating product comprising a pocketed coil spring assembly surrounded in an upholsted covering and associated method of manufacture.
The pocketed spring assembly comprises a plurality of parallel strings of springs joined to each other, each of the strings of springs comprising a row of interconnected pockets. Each of the pockets contain at least one coil spring encased in fabric. Each of the coil springs having an upper end turn, a lower end turn and a plurality of central convolutions between the end turns. Preferably, each string of springs is made of one piece of fabric folded and welded into a plurality of pockets, each of the pockets containing at least one coil spring. Opposed plies of the string of springs may be joined be sewing, gluing or sonic welding, as know in the art.
In each of the embodiments of the present invention, the pocketed spring assembly is posturized, meaning select sections, areas or regions of the pocketed spring assembly are firmer than other sections, areas or regions of the pocketed spring assembly. This difference in firmness is attributable to incorporating different numbers of coil springs into the pockets of fabric within the different sections, areas or regions of the pocketed spring assembly. The coil springs may be all made of the same gauge wire or made of different gauge wire.
Within the posturized pocketed spring assembly, select pockets of select strings of springs contain an outer coil spring and an inner coil spring, while other pockets of select strings of springs contain only one coil spring. The inner coil spring extends between said end turns of the outer coil spring and is wound generally coaxially with the outer coil spring such that the end turns of the inner and outer coil springs are adjacent one another. The areas of the pocketed spring assembly in which the pockets contain two coil springs are firmer than the areas of the pocketed spring assembly in which the pockets contain only one coil spring.
Although two coil springs are illustrated and described in select pockets of select strings of springs, more than two coil springs may be nested inside such pockets if desired. Similarly, springs other than coil springs may be used in accordance with the present invention, if desired.
One or more layers of padding may be placed on top of the pocketed coil spring assembly. An upholstered covering surrounds the padding and pocketed spring assembly. At least one border wire may be secured to the spring assembly, if desired.
In one embodiment of the present invention, the perimeter of the product has a greater firmness than the remaining central portion of the product due to the pockets around the perimeter of the product having at least two coil springs while the pockets in the central portion of the product have only one coil spring therein.
In other alternative embodiments, the product is divided into longitudinally spaced regions of differing firmnesses. In one such embodiment, the product has three longitudinally spaced regions of differing firmnesses, a head section, a center section and a foot section. The firmness of the center section is greater than the firmness of the head and foot sections due to the pockets of the center section having at least two coil springs therein while the pockets in the head and foot sections of the product have only one coil spring therein.
In another such embodiment, the product has four longitudinally spaced regions of differing firmnesses: a head section, upper and lower lumbar sections and a foot section. The firmness of the upper and lower lumbar sections being greater than the firmness of the head and foot sections due to the pockets of the upper and lower lumbar sections having at least two coil springs therein while the pockets in the head and foot sections of the product have only one coil spring therein.
In accordance with the present invention, a bedding or seating product may have any number of sections of different firmness oriented longitudinally or transversely due to the number of coil springs inside the pockets which are located within the sections.
In any of the embodiments described above, the strings of springs may be oriented transversely or longitudinally. Depending upon the desired application, all the pockets within a string of springs may contain two coil springs. Alternatively, only select pockets within a string of springs may contain two coil springs for improved firmness in select areas.
The method of manufacturing the posturized spring assembly of the present invention varies depending upon the desired posturization. However, in each of the applications of the present invention whenever two coil springs are to be inserted into a pocket, the inner spring is nested inside the outer spring to form a spring group prior to the spring group being inserted into the pocket of the string of springs.
In one method of manufacturing a posturized bedding or seating product in accordance with the present invention, only one coil spring is inserted into select pockets of a string of springs while two coil springs are inserted into other pockets of the string of springs. Once all of the pockets have been filled with at least one coil spring, the pockets are closed. Alternatively, each pocket may be closed immediately after the coil spring or coil springs is inserted therein. The finished string of springs is then joined to adjacent finished strings of springs to form a spring assembly. The adjacent strings of springs may be manufactured the same way or alternatively have each pocket of the string contain only one coil spring or two coil springs, i.e. be uniform along its length.
In each of the embodiments of the present invention, incorporating different numbers of coil springs into the pockets of the strings of springs results in a posturized pocketed spring assembly after multiple strings of springs are joined. Such a product may be made in accordance with a customer""s needs and desires quickly and easily.